Led lamp

ABSTRACT

A LED lamp includes LED modules. Each of the LED modules includes a heat sink body having a first terminal, a second terminal opposite to the first terminal, an airway having an opening at the second terminal, and a side hole on the side surface of the body. The side hole communicates with the corresponding airway. The LED modules are aligned to form concentric circles including an inner circle and an outer circle. The length between the first and the second terminals of each LED module at the inner circle is longer than that at the outer circle. Accordingly, heat generated by LEDs on the first terminals can be dissipated through the airways and the heat sink bodies.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priorities of Chinese application No.201610586654.6 filed on Jul. 22, 2016, Chinese application No.201610826238.9 filed on Sep. 14, 2016, and Chinese application No.201610854761.2 filed on Sep. 27, 2016, and the entirety of which isincorporated by reference herein.

BACKGROUND Technique Field

The present invention relates to an LED lamp and in particular relatesto an LED lamp comprising at least one LED module with a characteristicof high heat-dissipation.

Description of the Related Art

LED lamps are widely used to replace conventional incandescent lamps inthe market because of their advantages of long life-time, small size andpower saving. Heat-dissipation is a very important consideration duringdesign. China laid-open publication No. 104251476A discloses an LEDmodule with a vertical convection heat-dissipation structure, comprisingan optical assembly, a substrate, an LED light source and a heat sink,wherein the optical assembly is fixedly connected to the heat sink. TheLED module further comprises a heat-dissipation column disposed on oneside of the heat sink, wherein a vent is formed in the central of theheat sink to form a vertical heat-dissipation structure. Accordingly, abetter heat-dissipation property can be provided to a lamp with narrowspace. However, the LEDs are usually distributed on the edge of thebottom surface of the heat sink which will result in an LED module witha larger size, and the vertical convection heat-dissipation will behighly reduced when more LED modules are incorporated. It's a tradeoffbetween the numbers of LED modules and the heat-dissipation. Besides,the conventional LED modules are suffering from the problems of lowrecycling rate, different heat sinks for different LED modules withvarious powers, and high costs for development of various LED modules.

In order to resolve above-mentioned disadvantages, China laid-openpublication No. 103322536A discloses an LED aluminum pipe drillingefficient heat-dissipation device, comprising a heat-dissipationaluminum plate, a plurality of mounting holes, a plurality of aluminumpipes installed in the mounting holes and located on the same side ofthe heat-dissipation aluminum plate, and a plurality of heat-dissipationholes are arranged on the aluminum pipes. Accordingly, the heatgenerated by the LEDs can be efficiently dissipated into air through thealuminum pipes and the heat-dissipation holes, and the LED aluminum pipedrilling efficient heat-dissipation device can be convenientlyinstalled. However, the numbers of the aluminum pipes corresponding tothe LEDs will increase with the numbers of LEDs, when many LEDs/pips areinstalled, the heat convection effect may be lowered even a plurality ofdrilling holes are formed on the crowded aluminum pipes.

SUMMARY

To address the above-mentioned issues, an LED lamp comprising at leastone LED module with high heat-dissipation effect is provided.

According to an embodiment of the LED lamp, the LED lamp comprises aplurality of LED modules. Each of the LED modules comprises a heat sinkbody having a first terminal, a second terminal opposite to the firstterminal, an airway having an opening at the second terminal, and atleast one side hole on the side surface of the body, the at least oneside hole communicates with the airway. The plurality of LED modules arealigned to form concentric circles including an inner circle and anouter circle. The length between the first and the second terminals ofeach of the plurality of LED modules at the inner circle is longer thanthe length between the first and the second terminals of each of theplurality of LED modules at the outer circle.

According to an embodiment of the LED lamp, the LED lamp furthercomprises a plate. The plate comprises a plurality of mounting holesthereon. Each of the plurality of LED modules comprises a connectingpart corresponding to one of the heat sink body. Each of the connectingpart is on the first terminal of the corresponding heat sink body. Theplurality of LED modules is connected with the plurality of mountingholes, respectively.

According to an embodiment of the LED lamp, the area between the innertangent line of the mounting holes on the inner circle and the outertangent line of the mounting holes on the outer circle is one to fourtimes of the total areas of the plurality of mounting holes.

According to an embodiment of the LED lamp, each of the plurality ofheat sink body comprises a stepped surface at the second terminal of theheat sink body. The stepped surface comprises an upper inclined surface,a lower inclined surface, and a shoulder surface connected between theupper and the lower inclined surfaces. A distance from the plate to thelower inclined surface of each of the plurality of LED module at theinner circle is longer than a distance from the plate o the upperinclined surface of each of the plurality of LED modules at the outercircle.

According to an embodiment of the LED lamp, the ratio of the height h1of the connecting part over the height H of the LED module is about 0.04to 0.25, and the ratio of the height h2 of the shoulder surface to theheight H of the LED module is about ⅙ to ½.

According to an embodiment of the LED lamp, a position of each of theopenings of the plurality of the LED modules at the inner circle ishigher than, from the plate, a position of each of the openings of theplurality of the LED modules at the outer circle.

According to an embodiment of the LED lamp, a position of each of theopenings of the plurality of the LED modules at the inner circle ishigher than, from the plate, a position of the corresponding secondterminal of the plurality of the LED modules at the outer circle.

According to an embodiment of the LED lamp, the LED lamp comprises aplurality of LED units. Each of the plurality of LED units comprisesthree of the plurality of LED modules adjacent to each other. One LEDmodule of each of the plurality of LED units is arranged on the innercircle and the other two LED modules of each of the plurality of LEDunits are arranged on the outer circle.

According to an embodiment of the LED lamp, each of the three LEDmodules of each of the LED units has a trench on the surface adjacent tothe other two LED modules. The longitudinal axes of the trenches aresubstantially parallel to the longitudinal axes of the heat sink bodiesof the LED units. The three adjacent trenches forms a channel with afirst aperture and a second aperture opposite to the first aperture.

According to an embodiment, a heat sink for an LED module comprises aheat sink body. The heat sink body has a first terminal, a secondterminal opposite to the first terminal, an airway having an opening atthe second terminal, and a side hole on the side surface of the body.The side hole communicates with the airway. A surface of the secondterminal is a stepped surface or an oblique surface.

According to an embodiment, the heat sink body comprises a steppedsurface. The stepped surface comprises an upper inclined surface, alower inclined surface, and a shoulder surface connected between theupper and the lower inclined surfaces. The longitudinal axis of theshoulder surface is substantially parallel to the longitudinal axis ofthe airway.

According to an embodiment, the shoulder is substantially on the samesurface as the longitudinal axis of the airway on.

According to an embodiment, the upper inclined surface and the lowerinclined surface are not substantially parallel to each other.

According to an embodiment, the heat sink body comprises an obliquesurface. the normal line to the oblique surface and the longitudinalaxis of the airway creates an acute angle.

According to above description, the longer length of the LED modules atthe inner circle than that at the outer circle increases efficiency ofheat-dissipation from the LEDs. The side holes and the airways couldindividually or jointly improve thermal convection of the LED modules.The arrangement of the LED modules and the plate further makes thesecond terminals at the inner circle exposed and not being blocked bythe second terminals at the outer circle. Hence, efficiency ofheat-dissipation is further improved. The stepped surfaces at the secondterminal increase the area of the opening of the airways at the secondterminals. Accordingly, thermal convection is further improved. Thefeature of the position of the openings of the airways at the innercircle are higher than that at the outer circle improves thermalconvection furthermore. The trenches of the plurality of LED units couldimprove the thermal convection as well.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a perspective view the embodiment 1 of the LED lamp.

FIG. 2 illustrates a de-assembled view of the LED lamp as illustrated inFIG. 1 after removing the LED modules.

FIGS. 3A˜3E illustrate perspective views of embodiments of the LEDmodules for the LED lamp as illustrated in FIG. 1.

FIG. 4 illustrates a perspective view of the embodiment 2 of the LEDlamp.

FIGS. 5A˜5E illustrate perspective views of embodiments of the LEDmodules for the LED lamp as illustrated in FIG. 4.

FIG. 6 illustrates a perspective view of the embodiment 3 of the LEDlamp.

FIG. 7 illustrates a de-assembled view of the LED lamp as illustrated inFIG. 6 after removing the LED modules.

FIG. 8 illustrates the angle α between the centers of two adjacentmounting holes of the same circle on the plate, and the angle β betweenthe edges of two adjacent mounting holes of the same circle on theplate.

FIG. 9 illustrates an exploded view of the LED lamp as illustrated inFIG. 6.

FIG. 10 illustrates a cross-sectional view of the LED lamp asillustrated in FIG. 6.

FIG. 11 illustrates a perspective view of another embodiment of the LEDmodule for the LED lamp in FIG. 6.

DETAILED DESCRIPTION

The making and using of the embodiments of the present disclosure arediscussed in detail below. However, it should be noted that theembodiments provide many applicable inventive concepts that can beembodied in a variety of specific methods. The specific exemplaryembodiments discussed are merely illustrative of specific methods tomake and use the embodiments, and do not limit the scope of thedisclosure. Furthermore, the terms “longitudinal axis”, “top”, “bottom”are used to distinctly explain the relative positions of the elementsdepicted in the embodiments instead to limit the scope of thisinvention. Moreover, the terms “substantially perpendicular” and“horizontal” are defined as ±30% of the standard definition thereof. Forexample, the standard definition of “substantially perpendicular” is 90degrees to a base line, but it is defined as the angle ranging between60 to 120 degrees in this present invention.

Exemplary Embodiment 1

The embodiment 1 will be described below with reference to theaccompanied FIGS. 1 to 4. First, please refer to FIG. 1, which is aperspective view of the embodiment 1 of an LED lamp 100. As illustratedin FIG. 1, the LED lamp 100 comprises a plate 4, a plurality of LEDmodules 1 mounted on the plate 4, a plastic casing 2 and a lamp base 3.The lamp base 3 is used to interconnect with a power supplying source(not shown) and provides electrical power to drive the LEDs (not shown)of the LED modules 1.

As illustrated in FIG. 2, the shape of the plate 4 is substantiallycircular, and plates with other suitable shapes can also be selected asthe plate 4 in other embodiments. A plurality of mounting holes 41 areformed on the plate 4, and each of the LED modules 1 is inserted intoeach of the mounting holes 41 and fastened therein to expose the LEDs(light emitting diodes) formed on the LED modules 1. The mounting holes41 of this embodiment are circular countersunk-head holes, and each LEDmodule 1 is supported by the structure of each circular countersunk-headhole. Countersunk-head holes with other shapes can also be chosen basedon the shape of the cross-section of the heat sink 10. As illustrated inFIGS. 1 and 2, each of LED modules 1 is independently mounted onto theplate 4 by being inserted into the corresponding mounting hole 41. TheLED modules 1 can also be assembled together first to form an assemblyof the LED modules, and the assembly of the LED modules is mounted ontothe plate 4 thereafter. As illustrated in FIG. 2, a plurality of screwholes 42 are formed on the plate 4 and located between the center of theplate 4 and the mounting holes 41. The bottom (not labeled) of theplastic casing 2 is fixed on the plate 4 by screwing with screws 5 fromthe screw hole 42 on the plate 4 to the screw holes 21 on the edge ofthe bottom of the plastic casing 2. The lamp base 3 formed on the top ofthe plastic casing 2 is used to connect with a corresponding lamp socket(not shown).

The LEDs 30 of the LED modules 1 are interconnected with each other forexample in series. In the embodiment where the LEDs are connected inseries, the in-series-connected LEDs are connected with a powersupplying source shown). Specifically, the LED at one end of thein-series-connected LEDs is connected with cathode of the powersupplying source and the LED at the other end of the in-series-connectedLEDs is connected with anode of the power supplying source. A wire hole(not shown) may be formed at the center of plate 4 (the center of thecircle tangent to the screw holes 42) so that after the LEDs installedon mounting holes 41 by a conductive wire (not shown), the conductivewire may pass through the wire hole to electrically connected to thelamp base 3 and power supplying source.

Next, please refer to FIG. 3A, which illustrates an LED module 1 asshown in FIG. 1. As illustrated in FIG. 3A, each of the LED modules,comprises a heat sink 10, a connecting part 20 capped on the heat sink10, and an LED 30 on the connecting part 20. The LED 30 may comprise anLED chip (not shown) packaged with a lead frame (not shown). The heatsink 10 comprises a heat sink body 101 having a first terminal (notlabeled) and a second terminal (not labeled) opposite to the firstterminal (not labeled), an airway 11 communicating the first terminal(not labeled) and the second terminal (not labeled), and a steppedsurface 13 at the second terminal (not shown) of the body 101. (Inanother embodiment, the airway 11 has opening at the second terminal,but does not communicate with outer air through the first terminal. Inother words, the end of the airway 11 at the first terminal is blocked.The body 101 of this embodiment is a hollow tube with a circularcross-sectional area, and the inlet and the outlet of the airway 11 areof the same diameter to ensure that the heat generated by the LED 30 canbe dissipated evenly. A hollow tube with a cross-sectional area of othershape such as rectangular can also be selected as the body 101 in otherembodiments. The body 101 can be made of materials with good thermalconductivities, such as aluminum alloy 1070, 1050, 6061 and 6063, andpreferably aluminum alloy 6063. The body 101 can also be made of othermaterials with good thermal conductivities in other embodiments. Theconnecting part 20 can be made of aluminum alloy, and preferablyaluminum alloy 6063. The connecting parts 20 corresponds to heat sinkbody 101 and are, respectively, on the first terminal of thecorresponding heat sink body. In one embodiment, the connecting part 20is joined with the heat sink 10 by a glue (not shown) with a highthermal conductivity, and the LED 30 is on the connecting part 20 by theglue (not shown) with a high thermal conductivity. By means of the gluewith a high thermal conductivity, the heat sink 10, the connecting part20 and the LED 30 can be easily joined together with less cost. Asillustrated in FIG. 3A, the ratio of the height h1 of the connectingpart 20 over the height H of the LED module 1 is about 0.04 to 0.25 toensure that an attractive appearance can be fabricated with minimalcost.

As illustrated in FIG. 3A, heat sink body 101 comprises a steppedsurface 13 at the second terminal (not labeled) of the body 101, whereis away from the connecting part 20. The airway 11 is partially exposedalong its axis by means of the stepped surface 13. The stepped surface13 comprises an upper inclined surface 131, a lower inclined surface133, and a shoulder surface 132 connected between the upper inclinedsurface 131 and the lower inclined surface 133. In the embodiment, theshoulder surface 132 extends along the longitudinal axis of the airway11, and preferably the shoulder surface 132 is substantially on the samesurface as the longitudinal axis of the airway 11 on. In one embodiment,the shoulder surface 132 may be substantially parallel to thelongitudinal axis of the airway 11. The ratio of the height h2 of theshoulder surface 132 over the height H of the LED module 1 is about ⅙to½. The angle created by the upper inclined surface 131 and thehorizontal surface (not labeled, the surface perpendicular to the axisof the heat sink body 101) is about 45 to 50 degrees. The angle createdby the lower inclined surface 133 and the horizontal surface (notlabeled) is about 43 to 48 degrees. The angle created by the shouldersurface 132 and the horizontal surface (not labeled) is about 43 to 90degrees. The upper inclined surface 131 and the lower inclined surface133 are oblique to the longitudinal axis of the airway 11, andpreferably the upper inclined surface 131 and the lower inclined surface133 are oblique to the longitudinal axis of the airway 11 with the sameinclined angle. Either the upper inclined surface 131 or the lowerinclined surface 133 can also be substantially perpendicular to thelongitudinal axis of the airway 11 in other embodiments.

In other embodiments, FIG. 3B illustrates another LED module 1 for theembodiment 1 of the LED lamp. The LED module 1 illustrated in FIG. 3Bfurther comprises at least one side hole 12 which is formed on the sidesurface of the body 101 adjacent to the connecting part 20 andcommunicates with the corresponding airway 11. The side holes 12 and itscorresponding airway 11 means the side holes 12 and the airway 11 on thesame heat sink body 101. As illustrated in FIG. 3B, there are four sideholes 12 evenly surrounding the side surface of the body 101. The numberof the side holes 12 of other embodiments can be 1, 2, 3 or more. Theexperiments indicate that a better chimney effect for heat dissipationcan be achieved by forming some but not too many side holes 12 on thecircumferential surface at the same axis position of the body 101. Thechimney effect of heat dissipation will be reduced once the side holes12 are formed at different axis positons of the body 101. As illustratedin FIG. 3B, the openings 121 of the side holes 12 are exposed on theside surface of the body 101, whereby a part of the hot air heated byLEDs 30 enters into the airway 11 through the side holes 12 and then thepart of hot air flows out of the heat sink body. The rest of the hot airheated by LEDs 30 can be directly dissipated through the airway 11. Theheat-dissipation can be enhanced by designing a desired angle betweenaxes of each side holes 12 and the airway 11. Preferably the axis ofeach of the side holes 12 is substantially perpendicular to the axis ofthe airway 11. Accordingly, the heat generated by the LED 30 can bedissipated directly into the airway 11 and indirectly into the airway 11through the side holes 12. The ratio of the radius of each side holes 12over the radius of the 11 airway is about ⅛to ⅗. Preferably, the body101 has a thickness of about 1.5 mm to 4 mm, and the ratio of the outerradius of the airway 11 over the outer radius of the body 111 is about0.5 to 0.8, and the distance from the center of the side holes 12 to theconnecting part 20 is about 6 mm.

When the LED module 1 is operated, the heat generated by the LED 30 isconducted to the connecting part 20 and the heat sink 10, and the airwithin the airway 11 is heated and expanded, then the hot air goes up tobe exhaled out of the heat sink 10, and the cold air subsequently entersinto the airway 11 via the side holes 12. Accordingly, a small-sizedheat-dissipation device with a good thermal convection can be achievedby the chimney effect mentioned above. As illustrated in FIG. 3B, theheat generated by each LED 30 on each heat sink 10 can be individuallydissipated through the corresponding airway 11 of each heat sink body.Accordingly, the heat generated by a plurality of LEDs can be moreefficiently dissipated respectively through corresponding airways thanthrough a same airway. Moreover, the size of the heat sink can begreatly minimized and the heat-dissipation efficiency can be highlyenhanced. In comparison with a device with the LEDs around the center ofthe plate 4 or a device with the LEDs surrounding the area correspondingto the center of the plastic casing 2, the above-mentioned embodimentwith the LED modules mounted around the outer edge of the plate 4 couldemit similar optical power but have the advantages of betterheat-dissipation efficiency, lower production cost, and smaller overallsize.

In other embodiments, as illustrated in FIGS. 3C and 3D, at least onechannel 202 is further formed on the side surface of the connecting part20 of the LED modules 1. Each channel 202 comprises an axial section(not shown) and a radial section (not shown) communicating with theaxial section. The axial section is communicates with the airway 11.Accordingly, the channel 202 provides another pathway for thermalconvection.

In other embodiments, as illustrated in FIG. 3E, the LED 30 on theconnecting part 20 of the LED module 1 as shown in FIG. 3D is furthercapped with a reflector 40 to prolong its lifetime. Similarly, the LED30 on the connecting part 20 of the LED modules 1 as shown in FIGS.3A˜3C can also be capped with the reflector 40. Furthermore, the chip(not shown) of the LED 30 of other embodiments can be further beencapsulated by a lens (not shown) to adjust the emitting angle of theLED lamp 100.

Exemplary Embodiment 2

The LED lamp 200 illustrated in FIG. 4 is similar to the LED lamp 100.The LED modules 5 of the LED lamps 200 is different from that of LEDlamp 100.

As illustrated in FIGS. 5A˜5E, the structure of the LED module 5 issimilar to that of the LED modules 1 as illustrated in FIGS. 3A˜3E. Theheat sink body 171 of the heat sink 17 of the LED module 5 has anoblique surface 14 at the second terminal instead of a stepped surface13. The normal line to the oblique surface 14 and the longitudinal axisof the airway 141 creates an acute angle. Preferably the angle is lessthan 60 degrees. The thermal convection can be enhanced by the obliquesurface 14 and the heat generated by the LED 30 can be dissipated moreefficiently. As for the side holes 12 and channel 202 illustrated inFIGS. 3B˜3E can also be formed on the LED module 5 illustrated in FIGS.5B˜5E to enhance the heat-dissipation of each LED 30. Details of theside holes 12 and channels 202 will not be repeatedly discussed.

Exemplary Embodiment 3

The embodiment 3 will be described below with reference to theaccompanied FIGS. 6 to 11. The LED lamp 300 of this embodiment issimilar to the LED lamp 100 disclosed in the embodiment 1 and the LEDlamp 200 disclosed in the embodiment 2. As illustrated in FIG. 6, theLED lamp 300 comprises a plate 4, a plurality of LED modules 1 or 5mounted on the plate 4, a plastic casing 2 and a lamp base 3. The lampbase 3 is used to interconnect with a power supplying source (not shown)and provides electrical power to drive the LEDs (not shown) of the LEDmodules 1 or 5. The LED modules 1 or 5 illustrated in FIGS. 3A˜3E andFIGS. 5A˜5E can all be utilized in the LED lamp 300 of this embodiment.The LED module 1 illustrated in FIG. 3E is taken as an example in thisembodiment for exemplary description.

As illustrated in FIGS. 6 and 9, the plurality of LED modules 1A and 1Bare aligned to form concentric circles including an inner circle and anouter circle. Each of the LED modules comprises a heat sink body havinga first terminal and a second terminal. The length between the firstterminal and the second terminal of each LED modules 1A at the innercircle is longer than that at the outer circle. Hereinafter, the LEDmodules at the inner circle is referred as inner LED modules 1A and theLED modules at the outer circle is referred as outer LED modules 1B. Theheight H1 (from the plate 4 to the top of the second terminal) of theinner LED module 1A is greater than the height H2 of the outer module1B. As illustrated in FIG. 6, the height of the lamp base relative tothe plate 4, height H1 (the height of the inner LED module 1A relativeto the plate 4), and height H2, the height of the outer LED module 1Brelative to the plate 4, decrease in order to form a tower-shaped LEDlamp 300. As illustrated in FIG. 10, the lower inclined surface 133 ofthe heat sink 10 in the inner LED module 1A is preferably higher thanthe upper inclined surface 131 of the heat sink 10 in the outer LEDmodule 1B. This tower-shaped LED lamp 300 possesses not only acharacteristic of high heat-dissipation but also an attractiveappearance with an advantage of power saving. The height of each heatsink 10 in the inner LED module 1A is about 60 to 100 mm, and the heightof each heat sink 10 in the outer LED module 1B is about 40 to 70 mm.The inner diameter of the heat sink 10 is about 8 to 16 mm, and theouter diameter of the heat sink 10 is about 14 to 20 mm. In otherembodiments, the design with an outer LED module 1B taller than an innerLED module 1A can also be adopted. In this embodiment, the secondterminal of the inner LED modules 1A are totally exposed and not blockedby the second terminals of the outer LED modules 1B. However, in anotherembodiment, the second terminals of the outer LED modules 1B may block aportion of the second terminals of the inner LED modules 1A. In anotherembodiment, the position of each of the openings of the inner LEDmodules 1A is higher than, from the plate 4, the position of theopenings of the outer LED modules 1B. Specifically, the openings of theinner LED modules 1A may be totally or partially higher than that ofouter LED modules 1B. In another embodiment, the position of theopenings of the inner LED modules 1A is higher than, from the plate, theposition of the corresponding second terminals of the outer LED modules1B. In other words, the second terminals of the outer LED) modules 1B myblock a portion of the openings of the airways at the second terminalsof the inner LED modules 1A.

As illustrated in FIG. 7, a plurality of mounting holes 41 are formed onthe plate 4 and arranged to surround the plastic casing 2 to form aninner circle (not labeled) and an outer circle (not labeled). The areabetween the inner tangent line A of the mounting holes 41 in the innercircle (not labeled) and the outer tangent line B of the mounting holes41 in the outer circle (not labeled) is almost 1 to 4 times of the totalareas of the mounting holes 41 in the inner circle (not labeled) and theouter circle (not labeled), and preferably 1.2 to 4 times of the totalareas of the mounting holes 41 in the inner circle (not labeled) and theouter circle (not labeled). FIG. 8 illustrates the angle α between thecenters of two adjacent mounting holes 41 of the same circle the plate4, and the angle β between the edges of two adjacent mounting holes 41of the same circle on the plate 4. The angle α is determined by thenumbers of LED modules 1, and preferably ranges from 18 to 40 degrees.The angle β is less than 10 degrees. The outer LED modules 1B of thisembodiment comprises about 15 to 25 LED modules 1, and the inner LEDmodule 1A of this embodiment comprises about 8 to 16 LED modules 1. TheLED modules 1 of the same circle are spaced with each other by about 10to 30 mm, and the LED modules 1 between the inner circle and outercircle are spaced with each other by about 14 to 22 mm.

As illustrated in FIGS. 9&10, the plate 4 further comprises a flange 43formed along the edge of the plate 4, wherein the inner surface 43 a ofthe flange 43 is inclined relative to the upper surface 4 a of the plate4, and a trench 6 is formed between the inner surface 43 a of the flange43 and the upper surface 4 a of the plate 4. Therefore, sufficient aircan be introduced into the thermal convection via the opening 121 of theside holes 12 by means of the trench 6 to facilitate the heatdissipation. The side holes 12 can be formed on lower side surface ofthe body 10 than before by means of forming the trench 6 to providesufficient air and elongate the path of thermal convection, whichprovides a heat sink with a smaller size and better thermal dissipation.

Please refer to FIG. 11. In this embodiment, the LED lamp comprises aplurality of LED modules arranged to form concentric circles includingan inner circle and an outer circle. The LED lamp comprises a pluralityof LED units 1′. Each of the plurality of LED units 1′ comprises threeof the plurality of LED modules 1A, 1B, 1C adjacent to each other. OneLED module 1A of each of the plurality of LED units 1′ is arranged atthe inner circle while the other two LED modules 1B, 1C of each of theplurality of LED units 1′ are arranged at the outer circle. Hereinafter,the LED module 1A at the inner circle is referred as the first LEDmodule 1A and the LED modules 1B, 1C at the outer circle are referred asthe second and third LED modules 1B, 1C. As illustrated in FIG. 11, thefirst LED module 1A, the second LED module 1B and the third LED module1C are attached to each other to form a triangle. Each of the three LEDmodules 1A, 1B, 1C of each of the LED units 1′ has a trench on thesurface adjacent to the other two LED modules. For example, a firsttrench 15 a is formed on the outer surface 1 a of the first LED module1A along the longitudinal axis of the first LED module 1A; a secondtrench 15 b is formed on the outer surface 1 b of the second. LED module1B along the longitudinal axis of the second LED module 1B; and a thirdtrench 15 c is formed on the outer surface 1 c of the third LED module1C along the longitudinal axis of the third LED module 1C. The firsttrench 15 a, the second trench 15 b and the third trench 15 c are linkedto each other to form a cavity 15 with a first aperture (not labeled)and a second aperture (not labeled) opposite to the first aperture (notlabeled). The cavity 15 can be functioned as an additional thermalconvection structure, which can further enhance the heat dissipation ofthe LED modules 1A, 1B, 1C of each of the LED units 1′. The shapes ofthe cross-sections of the trench 15 a, 15 b and 15 c are arcs with anarc angle of around 120 degrees, in this embodiment. In otherembodiments, trenches with suitable cross-sectional areas can also beselected as the trenches 15 a, 15 b and 15 c. The LED lamp can compriseat least one of the LED unit 1′, and the LED unit 1′ can comprise morethan 3 LED modules.

As mentioned above, the LED modules of some embodiments can be selectedand assembled in many ways to generate LED lamps with various power,which can not only reduce the fabrication cost but also facilitate theassembly of the LED lamps.

While the invention has been described by way of example and in terms ofthe preferred embodiments, it is to be understood that the invention isnot limited to the disclosed embodiments. To the contrary, it isintended to cover various modifications and similar arrangements (aswould be apparent to those skilled in the art). Therefore, the scope ofthe appended claims should be accorded the broadest interpretation so asto encompass all such modifications and similar arrangements.

What is claimed is:
 1. An LED lamp, comprising: a plurality of LED modules, each of the LED modules comprising a heat sink body having a first terminal, a second terminal opposite to the first terminal, an airway having an opening at the second terminal, and at least one side hole on the side surface of the body; wherein the at least one side hole communicates with the corresponding airway, the plurality of LED modules are aligned to form concentric circles including an inner circle and an outer circle, and the length between the first and the second terminals of each of the plurality of LED modules at the inner circle is longer than the length between the first and the second terminals of each of the plurality of LED modules at the outer circle.
 2. The LED lamp as claimed in claim 1, further comprising a plate, wherein the plate comprises a plurality of mounting holes thereon, each of the plurality of LED modules comprises a connecting part corresponding to one of the heat sink body, each of the connecting part is on the first terminal of the corresponding heat sink body, and the plurality of LED modules is respectively connected with the plurality of mounting holes.
 3. The LED lamp as claimed in claim 2, wherein the area between the inner tangent line of the mounting holes on the inner circle and the outer tangent line of the mounting holes on the outer circle is one to four times of the total areas of the plurality of mounting holes.
 4. The LED lamp as claimed in claim 3, wherein each of the plurality of heat sink body comprises a stepped surface at the second terminal of the heat sink body, the stepped surface comprises an upper inclined surface, a lower inclined surface, and a shoulder surface connected between the upper and the lower inclined surfaces, and a distance from the plate to the lower inclined surface of each of the plurality of LED module at the inner circle is longer than a distance from the plate to the upper inclined surface of each of the plurality of LED modules at the outer circle.
 5. The LED lamp as claimed in claim 4, wherein the ratio of the height h1 of the connecting part over the height H of the LED module is about 0.04 to 0.25, and the ratio of the height h2 of the shoulder surface to the height H of the LED module is about ⅙to ½.
 6. The LED lamp as claimed in claim 3, wherein a position of each of openings of the plurality of the LED modules a the near circle is higher than, from the plate, a position of each of the openings of the plurality of the LED modules at the outer circle.
 7. The LED lamp as claimed in claim 3, wherein a position of each of the openings of the plurality of the LED modules at the inner circle is higher than, from the plate, a position of the corresponding second terminal of the plurality of the LED modules at the outer circle.
 8. The LED lamp as claimed in claim 2, wherein the plate further comprises a flange along the edge of the plate.
 9. The LED lamp as claimed in claim 8, wherein an inner surface of the flange is inclined relative to an upper surface of the plate, and a trench is between the inner surface of the flange and the upper surface of the plate.
 10. The LED lamp as claimed in claim 1, wherein the LED lamp comprises a plurality of LED units, each of the plurality of LED units comprises three of the plurality of LED modules adjacent to each other, one LED module of each of the plurality of LED units is arranged on the inner circle and the other two LED modules of each of the plurality of LED units are arranged on the outer circle.
 11. The LED lamp as claimed in claim 10, wherein each of the three LED modules of each of the LED units has a trench on the surface adjacent to the other two LED modules, the longitudinal axes of the trenches are substantially parallel to the longitudinal axes of the heat sink bodies of the LED units, the three adjacent trenches forms a channel with a first aperture and a second aperture opposite to the first aperture.
 12. The LED lamp as claimed in claim 11, the shape of the cross-section of each of the trenches is arc with an arc angle of 120 degrees.
 13. The LED lamp as claimed in claim 1, wherein each of the plurality of LED modules comprises at least one LED, the LEDs are connected with each other in series, and the in-series-connected LEDs are connected with a power supplying source.
 14. A heat sink for an LED module, comprising a heat sink body, the heat sink body haying a first terminal, a second terminal opposite to the first terminal, an airway having an opening at the second terminal, and at least one side hole on the side surface of the body and communicating with the airway, wherein a surface of the second terminal is a stepped surface or an oblique surface.
 15. The heat sink for the LED module as claimed in claim 14, wherein the heat sink body comprises a stepped surface, the stepped surface comprises an upper inclined surface, a lower inclined surface, and a shoulder surface connected between the upper and the lower inclined surfaces, and the longitudinal axis of the shoulder surface is substantially parallel to the longitudinal axis of the airway.
 16. The heat sink for the LED module as claimed in claim 15, wherein the shoulder is substantially on the same surface as the longitudinal axis of the airway on
 17. The heat sink for the LED module as claimed in claim 15, wherein the upper inclined surface and the lower inclined surface are not substantially parallel to each other.
 18. The heat sink for a LED module as claimed in claim 15, wherein the upper inclined surface and the lower inclined surface are substantially perpendicular to the longitudinal axis of the airway.
 19. The heat sink for the LED module as claimed in claim 15, wherein the upper inclined surface and the lower inclined surface are substantially parallel to each other.
 20. The heat sink for the LED module as claimed in claim 14, wherein the heat sink body comprises an oblique surface, the normal line to the oblique surface and the longitudinal axis of the airway creates an acute angle.
 21. The heat sink for the LED module as claimed in claim 14, wherein the shape of the cross-section of the heat sink body along a surface perpendicular to the longitudinal axis of the heat sink body is circular or rectangular. 